ROCHESTER, Minn., April 15, 2008 /PRNewswire-USNewswire/ -- A new MayoClinic study found that young-onset dementia often is caused byneurodegenerative or autoimmune/inflammatory conditions, but only rarely byAlzheimer's disease. This differs substantially from the common causes ofdementia in older individuals (Alzheimer's disease and otherneurodegenerative dementias). These findings will be presented at theAmerican Academy of Neurology Annual Meeting in Chicago on April 15.

Dementia represents a progressive decline in a person's cognitivefunction that affects the ability to think, speak, reason, remember andmove. The most common forms of dementia are Alzheimer's disease, vasculardementia and Lewy body dementia. Approximately 12 in 100,000 people maydevelop dementia prior to age 45, called young-onset dementia.

"After seeing several patients in their 20s who had graduated fromcollege and were suddenly experiencing severe dementia, I wanted to try toprovide answers as to what was causing dementia at such young ages," saysBrendan Kelley, M.D., an author of this study and a neurologist at MayoClinic.

Dr. Kelley and a team of Mayo Clinic physicians set out to identify thecharacteristics and causes of dementia prior to age 45. They identified 235individuals, ages 17 to 45, who previously had normal cognitive functionand were evaluated for progressive cognitive decline at Mayo Clinic from1996 to 2006. In one-third of patients, the dementia was caused by aneurodegenerative disorder such as frontotemporal dementia, Huntington'sdisease or familial prion disease. However, Alzheimer's disease was anuncommon cause. In 20 percent of patients, young-onset dementia was causedby autoimmune or inflammatory conditions such as multiple sclerosis,autoimmune encephalopathy or neuropsychiatric lupus. According to Dr.Kelley, this is an important finding, because many of these diseases mayhave specific treatments.

"This study sheds light on the fact that young people do, in fact,develop dementia, and that there are important differences between thecauses of young-onset dementia and the causes of dementia in olderindividuals," says Dr. Kelley. "However, more research is required tobetter understand the characteristics and most effective treatments foryoung patients with dementia."

Brad Bishop is one of the patients who influenced Dr. Kelley to pursuethis research. Bishop, age 27, was diagnosed with frontotemporal dementiain 2006. According to his parents, he was an energetic, thoughtful, caringand intelligent young man who graduated from college in 2004 with a doublemajor in business and computers. His symptoms of dementia started aroundage 21, including withdrawal from people outside his family, inappropriatebehavior, poor financial judgment and progressive decline in cognitivefunction. Now, Bishop needs around-the-clock care as his brain continues todeteriorate.

"We are seeing our son disappear before our eyes, little bit by littlebit," says Susan Bishop, his mother. "We'll always hope for a miracle, butrealistically we just want Brad to be safe, happy, comfortable and treatedwith the dignity and respect that he deserves...every day we have with himis a gift."

Dr. Kelley and his team will continue to learn more by prospectivelyfollowing patients like Bishop to better understand what causes early-onsetdementia. Other members of the Mayo Clinic research team included BradleyBoeve, M.D., and Keith Josephs, M.D.

To obtain the latest news releases from Mayo Clinic, go tohttp://www.mayoclinic.org/news. MayoClinic.com (http://www.mayoclinic.com)is available as a resource for your health stories.